Tomatoes descended from a Peruvian wild ancestor which spread across South and Central America, and was introduced to Europeans as “tomatl” by natives of Mexico. Until around 1840, they were thought poisonous or harmful by Europeans, who called them “cancer apple” and grew them as a curiosity. Their palatability was eventually discovered and gradually the varieties that we know today were developed. There are hundreds of varieties, serving many purposes and having many qualities. The tomato is probably the most cultivated crop by home gardeners.
Tomatoes are heavy feeders, requiring a lot of Nitrogen to bear good fruit. They also require lots of heat, being a tropical plant. Young plants are very sensitive, and should never be put out before the last frost.
Tomatoes can be started indoors about six weeks early, either under a grow light or flourescent light, or by a south-facing window. Don’t rotate them as they do better when allowed to self-orient to the sunlight. Brush them lightly with your hand every day or set a fan to blow air over them; this makes the stems stronger.
Seed starting mix shouldn’t be too rich. Vermiculite or a mix of vermiculite, sand, peat, and a little compost will do. At least two inches of soil depth is necessary. Four inches is better, since roots need room to develop for proper growth. Seperate or conjoined pots are better than seed flats. Seeds should germinate in about a week at 70 to 80 degrees Fahrenheit, or about two weeks at 60 degrees.
Here’s the tricky part: Water enough so the plants don’t dry out, but don’t overwater. Too much water is bad for young plants and may breed fungus in the soil. Allow the soil to almost dry out. Then flood the plants so the soil is saturated. This can be a difficult balance to achieve, but will yield better results.
Locate the tomato bed on a south-facing slope in plenty of sun. Plan for the adult plants to have eighteen to twenty-four inches between them (depending, of course on the size of the variety you choose; consult your seed catalog).
Tomatoes prefer slightly acid soil, about pH 5.5 to 6.8. Prepare the planting bed with about an inch of compost. Too much at first stimulates leaf growth at the expense of roots, which must develop first. Black plastic can be used to warm the soil bed, and makes a good mulch.
“Harden” seedlings off before transplanting by placing them outside on warm days for a few hours, bringing them back in at night. Expose them to direct sunlight gradually.
Transplanting is best done on a cloudy day to avoid sunscald. Plants raised indoors are initially susceptible to sunscald. Soaking the soil with compost tea will give the roots a good start. Hold seedlings by a seed leaf when transplanting and set deeper than they were in the starter mix. This gives them a chance to root better from the buried part of the stem. Water daily at first.
It is a good idea to protect the transplanted seedlings from cold. Various devices may be used, including cold frames, cloches, cups, and row covers. A plastic soda bottle with the bottom cut off makes a good cloche (pin it down so it won’t blow off). Mulching with two to four inches of straw or hay will retain moisture and protect roots from summer heat.
Tomatoes come in two basic types: Determinate (or bush types) and indeterminate (or vine types). Determinate types usually grow about three flower clusters and stop, while indeterminate types keep growing until fall frost kills the plant. Indeterminate tomatoes usually require pruning for best results. Leaving the top sprout growing, pinch or cut any small “suckers” that sprout off the main stem where lower leaf clusters meet the stem.
Otherwise these suckers will grow very large, robbing vigor from the main plant stem and making the whole plant unruly and hard to maintain. Cut suckers when they are about three to six inches long. Train the main stem by tying loosely with rags or soft twine on a stake (usually about five to seven feet tall), or grow inside a tomato cage, or on a trellis or fence. There are many methods for supporting the vining tomatoes and you may invent your own. Bush tomatoes may or may not require some support.
When your tomatoes set fruit you may start heavier feedings of nitrogen. Pull back the mulch and put down compost or other nitrogen-rich fertilizers, then replace and deepen the mulch. Or water with compost tea, fish emulsion, or other nitrogen-rich liquid fertilizer. Water more as the weather heats up. Tomatoes won’t set fruit above 90 degrees Fahrenheit, but will set more fruit as weather cools again.
Pick fruits when ripe or almost ripe, but don’t let overripen. As the end of the season approaches, cut off blossoms and small fruits so the plant puts its energy into ripening fruits. Mature fruits may be ripened indoors in a cool place away from direct sunlight.